The politics of conservative elites and the 'liberal media' argument

Recent evidence suggests that conservative elites' claims of a liberal media are having an impact upon public perceptions of news coverage. With this in mind, we examined two related questions in the context of the 1988, 1992, and 1996 presidential elections. First, what factors may be prompting conservative elites to make allegations of liberal media bias? Second, what factors may influence when news media report these criticisms during presidential campaigns? Findings suggest that these criticisms of news media are at least partly strategic and reflect a dynamic relationship between political elites and journalists during a presidential campaign.     

Improved Performance of Molecular Bulk‐Heterojunction Photovoltaic Cells through Predictable Selection of Solvent Additives

Solvent additives provide an effective means to alter the morphology and thereby improve the performance of organic bulk‐heterojunction photovoltaics, although guidelines for selecting an appropriate solvent additive remain relatively unclear. Here, a family of solvent additives spanning a wide range of Hansen solubility parameters is applied to a molecular bulk‐heterojunction system consisting of an isoindigo and thiophene containing oligomer as the electron donor and [6,6]‐phenyl‐C₆₁‐butyric acid methyl ester (PC₆₁BM) as the electron acceptor. Hansen solubility parameters are calculated using the group contribution method and compared with the measured solubilities for use as a screening method in solvent additive selection. The additives are shown to alter the morphologies in a semipredictable manner, with the poorer solvents generally resulting in decreased domain sizes, increased hole mobilities, and improved photovoltaic performance. The additives with larger hydrogen bonding parameters, namely triethylene glycol (TEG) and N‐methyl‐2‐pyrrolidone (NMP), are demonstrated to increase the open circuit voltage by ~0.2 V. Combining a solvent additive observed to increase short circuit current, poly(dimethylsiloxane), with TEG results in an increase in power conversion efficiency from 1.4 to 3.3%.     

Potential phytotoxic components of pulverised fuel ash

The release of aluminium, arsenic, boron, cobalt, copper, chromium, manganese, nickel, lead and zinc from pulverised fuel ash (PFA) and a standard Wellesbourne soil were studied by extraction with nitric acid and EDTA and by anaerobic incubation with grass meal. According to each of the criteria, only aluminium, arsenic, boron and copper were released in appreciably greater quantities from PFA than from soil. There were considerable variations in pH and the total content of soluble salts, mainly sodium, potassium, magnesium and calcium sulphates, between samples of ash. pH varied from 4.6 to 9.3 and the conductivity declined from 4.75 × 10^?3 to 3.2 × 10^?3 ohm^?1 cm^?1 with increased pH. The pH of the ash also influenced the concentration of other ions in water in equilibrium with it. When the pH was low the concentrations of aluminium and copper were large but those of arsenic were small. By contrast, when pH was high, the concentrations of arsenic were substantial and those of aluminium and copper small. The concentrations of boron, though always substantial, declined with increase in pH. It is concluded that, in addition to sulphate and boron, aluminium, copper and arsenic are potential causes of phytotoxicity.     

High-temperature oxidation of Pt-45Pd-10Rh

The surfaces of Pt-45Pd-10Rh foils oxidized over the range 875–1075 K in a 20% O₂-Ar mixture at atmospheric pressure were examined by Auger electron, X-ray photoelectron, and Raman spectroscopy. The composition of the oxide formed on the surface was found to vary with temperature from predominantly PdO at 875 K to PdRhO₂ at 1075 K. Only a few atomic percent Pt was observed, present in both the metallic and (apparently) +1 oxidation states at 875 K and in the metallic state at 1075 K. The formation of PdRhO₂ (and no Rh₂O₃) at 1075 K was found to persist upon reoxidation following a low-temperature reduction cycle in which the increased Rh concentration on the surface was retained. An oxidation-induced Rh enrichment of the surface of the alloy foil beyond 50 at. % does not appear likely within the temperature/pressure regime investigated.     

PdRhO2 formation during the air oxidation of a Pd-15Rh alloy

The surfaces of air-oxidized Pd-15Rh alloys have been examined by X-ray photoelectron spectroscopy (XPS) and by Raman spectroscopy. The XPS results indicate that the near-surface region of samples oxidized in the temperature range 1075 to 1125 K contains Pd in both the +2 and +1 oxidation states and Rh in the +3 oxidation state. The ratio of Pd (I) to Rh (III) is found to be 11. Raman spectra confirm that two Pd-containing phases, PdO and PdRhO₂, are present in the near-surface region and eliminate the possibility that Rh₂O₃ is present. Also, a resonant Raman effect is observed in anhydrous PdO for exciting wavelengths in the vicinity of 500 nm.     

A formal approach to specifying assembly operations

Experience has proved that exploiting robots for assembly tasks is much more difficult than manufacturing engineers had expected and many attempts at implementing robotic assembly have failed. Our research has led us to believe that a formal approach to specifying the steps required for assembly would be of great benefit in developing the required software for a specific task, and in adaptively controlling and monitoring the execution of robotic assembly steps. The US National Bureau of Standards has developed a formal system, called ABC (for Assembly By Constraints) for specifying the steps required for assembly. The system is based on the reduction in the degrees of freedom of objects as they are assembled. Using this basic concept, we have developed 14 primitive operations which can be used to completely specify assembly steps for a large class of problems. This paper initially outlines the historical development of the system, then describes two pieces of software developed to allow easy definition of assembly tasks using the ABC system, and finally presents two practical examples.     

Humidity Sustained Wearable Pouch‐Type Triboelectric Nanogenerator for Harvesting Mechanical Energy from Human Activities

Triboelectric nanogenerators (TENGs) are gaining much research interest recently owing to their facile and cost‐effective device structure. However, the effect of relative humidity (in moisture atmosphere) on the output performance still needs to be resolved. Herein, a pouch‐type TENG is proposed to significantly reduce the effect of relative humidity on its electrical output and a stable performance is also attained in a humid environment. In this regard, a dielectric and dielectric materials‐based TENG (DD‐TENG) is first developed using nanoarchitecture polydimethylsiloxane (NA‐PDMS) and multiwalled carbon nanotube/nylon composite layers as a triboelectric material with the negative and positive tendencies, respectively. The NA‐PDMS and nylon composite layers play a key role in increasing the surface contact area and surface charge density between the dielectric/triboelectric materials as well as the output performance of DD‐TENG. However, the DD‐TENG device exhibits a stable and high output performance with the effective output power density of ≈25.35 W m^?2. Additionally, the performance of the pouch‐type DD‐TENG device is not almost affected even though the relative humidity is increased from 35 to 81%, while it is dramatically decreased for the nonpouch‐type device. Finally, the pouch‐type DD‐TENG is employed as a wearable device to effectively harvest the mechanical energy from daily human activities.     

Discrete-time Markov Model for Wireless Link Burstiness Simulations

Link burstiness can negatively affect the performance of wireless networking protocols, by causing an extra of 15 % transmission cost. It describes the underlying behavior of packet delivery and provides insights into tuning protocols to improve performance. In this paper, we propose a discrete-time Markov model to simulate the burstiness behavior of wireless links, which provides a novel approach for link burstiness studies. More specifically, we first present a discrete-time Markov model with the input of $\beta $ value and the output of a sequence trace of burstiness traffic. Then we design an algorithm to simulate the Markov model, where the state transition represents the packet receptions or losses. Finally, we evaluate the proposed model in terms of distribution of link burstiness, accuracy and cost, and the results demonstrate that our model is able to accurately simulate the burstiness behavior.     

InAlSb/InAs/AlGaSb Quantum Well Heterostructures for High-Electron-Mobility Transistors

Heterostructures for InAs-channel high-electron-mobility transistors (HEMTs) were investigated. Reactive AlSb buffer and barrier layers were replaced by more stable Al_0.7Ga_0.3Sb and In_0.2Al_0.8Sb alloys. The distance between the gate and the channel was reduced to 7–13 nm to allow good aspect ratios for very short gate lengths. In addition, n⁺-InAs caps were successfully deposited on the In_0.2Al_0.8Sb upper barrier allowing for low sheet resistance with relatively low sheet carrier density in the channel. These advances are expected to result in InAs-channel HEMTs with enhanced microwave performance and better reliability.     

Interacting effects of tillage method,nitrogen fertiliser and secondary drainage on winter wheat production on a calcareous clay soil

The response of winter wheat to nitrogen fertiliser within the range 0–200 kg ha^?1 in 40 kg increments applied either in April or in May in two consecutive seasons (1976–77 and 1977–78) was tested in a field experiment on a calcareous clay soil that was either direct-drilled, shallow tine cultivated (5–8 cm), or mouldboard ploughed (23 cm). These cultivation methods had been used on the same plots in the four preceding seasons (1973 to 1976) in a comparison of cultivation systems. A comparison was also made with direct-drilling on land that had been deep tine cultivated (17 cm) during the 1973–76 experiment. In the second season (1977–78) effects were examined of newly drawn mole drains, on land that had been direct-drilled or ploughed. In both seasons the effect of cultivation method on grain yield was small when nitrogen fertiliser was applied at 80–120 kg N ha^?1. Nitrogen top dressings in April gave heavier yields than the equivalent dressings in May, partly because of dry weather after the May applications in both years. There was no interaction between method of cultivation and amount of nitrogen applied in 1976–77, but a significant interaction was detected in 1977–78 which was probably associated with less nitrogen being available in the uncultivated soil during the winter and spring. The results show that the potential yield of direct-drilled crops may have been underestimated in some earlier comparisons of different methods of cultivation where small uniform top dressings of nitrogen were applied to each cultivation treatment. Mole drainage increased yield especially at low rates of nitrogen and after direct drilling, These results indicate that direct-drilled and ploughed land may differ in their drainage requirements.